docstr: When using online data, update model in each bar as the following steps:
      - update dataset with online data, the dataset should support online update
      - make the latest prediction scores of the new bar
      - update the pred score into the latest prediction
docstr_tok: ["When","using","online","data",",","update","model","in","each","bar","as","the","following","steps",":","-","update","dataset","with","online","data",",","the","dataset","should","support","online","update","-","make","the","latest","prediction","scores","of","the","new","bar","-","update","the","pred","score","into","the","latest","prediction"]
code: def _update_model(self) -> None:
      """
      When using online data, update model in each bar as the following steps:
          - update dataset with online data, the dataset should support online update
          - make the latest prediction scores of the new bar
          - update the pred score into the latest prediction
      """
      # TODO: this method is not included in the framework and could be refactor later
      raise NotImplementedError("_update_model is not implemented!")
  
file_path: qlib/qlib/backtest/signal.py
imports: import abc
  from typing import Dict, List, Text, Tuple, Union
  import pandas
  from qlib.utils import init_instance_by_config
  from ..data.dataset import Dataset
  from ..data.dataset.utils import convert_index_format
  from ..model.base import BaseModel
  from ..utils.resam import resam_ts_data
label_desc: Use image node_id 2 for calling the ModelSignal obj's underlying member method code with example usage: obj._update_model() without return types